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Biomedical subjects

David G Addiss

Publications and source records attributed to David G Addiss.

At least 19 recordsLinked to original sources

Health-seeking behaviors and self-care practices of Dominican women with lymphoedema of the leg: implications for lymphoedema management programs.

BACKGROUND: In the Dominican Republic, a Latin American country with filariasis-endemic areas, more than 63,000 people have lymphatic filariasis and more than 400,000 people are at risk of future infection. In this paper, we explore the health beliefs, health-seeking behaviors and self-care practices of women with lymphoedema in filariasis-endemic areas to better understand the needs of women when developing lymphoedema morbidity control programs. METHODS: Qualitative data were collected through semi-structured interviews of 28 women, 3 focus group discussions with 28 women, field notes and photographs. RESULTS: Women described exhaustive and expensive attempts at seeking a cure for their lymphoedema. Family members were influential in providing women with initial care seeking referrals to indigenous healers credited with influence over physical, mental, spiritual and supernatural properties of illness. When indigenous treatments proved to be ineffectual, the women sought care from trained healthcare providers. Most healthcare providers incorrectly diagnosed the edema, failed to adequately treat and meet the needs of women and were viewed as expensive. Most women resorted to self-prescribing injectable, oral, or topical antibiotics along with oral analgesics as a standard practice of self-care. CONCLUSION: Healthcare providers must understand a woman's cultural perspectives of illness, her natural networks of support and referral, her behavioural practices of care-seeking and self-care and the financial burden of seeking care. In the culture of the Dominican Republic family members and traditional healthcare providers are influential advisors on initial health-seeking behaviors and self-care practices. For this reason family-oriented interventions, support groups for women and their families, community education and training on simple, low cost lymphoedema management techniques for indigenous healers are viable ways to influence the early detection, diagnosis and treatment of women with lymphoedema. The extensive use of injectable, oral and topical antibiotics by indigenous healers and women without medical supervision suggests a need for health education messages related to the risks of such practices.

Journal Article↗

A survey of treatment practices and burden of lymphoedema in Togo.

Lymphatic filariasis, a mosquito-borne parasitic disease, can lead to lymphoedema and elephantiasis. This study describes the results of a baseline survey of a lymphoedema morbidity management programme in Togo. A convenience sample of 188 people with lymphoedema was asked about symptoms, treatment preferences and quality of life. Those with higher stage lymphoedema were more likely to have experienced an acute attack (odds ratio=1.9; P=0.002). Although only 28.2% of those surveyed reported currently using any lymphoedema treatment, 80.3% had used treatments in the past, primarily traditional products (68.1%) and scarification (38.8%). Medication was the preferred treatment for acute attacks, both currently (73.1%) and in the past (61.7%). Patients reported difficulties performing activities such as walking to the field (44%) and carrying a heavy load (63%) as a result of their lymphoedema. Patients felt avoided by their family (17%) and their community (36%). Using the Duke Anxiety-Depression scale, over 70% of patients were found to be at high risk of depression and this risk increased with lymphoedema stage (P=0.04). The survey results demonstrate the need for a morbidity management programme that will increase the use of morbidity management techniques and decrease the physical and emotional burden of this disease.

Acute Disease↗

Participation in three consecutive mass drug administrations in Leogane, Haiti.

OBJECTIVES: In the global effort to eliminate lymphatic filariasis, mass drug administrations (MDAs) are organised annually. The success of this strategy depends on achieving high levels of drug coverage, which reduce the number of persons with circulating microfilariae and consequently transmission. Persons who consistently fail to participate in MDAs represent a potential threat to the goal of filariasis elimination. We wanted to know the drug coverage, the proportion of persons who were systematically non-compliant and factors associated with this behaviour. METHODS: We conducted three surveys following the third annual MDA of a filariasis elimination program in Leogane, Haiti: (1) a total population survey to determine coverage; (2) an adult survey to determine non-compliance and associated factors and (3) an urban survey to make a rural-urban comparison. RESULTS: During the third MDA, the overall surveyed coverage was 78.5% [95% confidence interval (CI) 74.4-82.6] A survey among adult population showed coverage estimates for persons >14 years old of 59.4% (95% CI 52.0-66.7), 61.0% (95% CI 55.0-67.4) and 67.3% (95% CI 60.5-74.0), for the first, second and third MDA respectively. The coverage in rural areas (78.3%) was significantly higher than in urban areas (68.3%, P < 0.05). Of the population > 14 years of age, 18% never took the drugs during any of three MDAs. These persons did not differ significantly from MDA participants by age, gender or other characteristics that we assessed. CONCLUSION: More research is needed to identify characteristics of systematically non-compliant persons in order to refine health education messages and improve distribution strategies to increase drug coverage.

Adolescent↗

Symptoms reported after mass drug administration for lymphatic filariasis in Leogane, Haiti.

Mass drug administration (MDA) for lymphatic filariasis (LF) can cause adverse reactions from microfilarial and adult worm death. Symptoms after the fifth annual MDA in Leogane, Haiti, were studied to determine whether they resulted from parasite death. Persons reporting post-MDA systemic symptoms at 5 of 148 drug distribution posts and men reporting scrotal pain at any post were interviewed. Participants were tested with immunochromatographic tests (ICTs), and men with scrotal symptoms were examined. At the five posts, 3,781 persons took anti-filarial medication. Of these, 314 (8%) returned with symptoms; the most common were headache (36%) and gastrointestinal complaints (28%). Of the 294 (94%) who consented to ICT testing, 47 (16%) were positive. Of 69 men with scrotal symptoms who consented to ICT testing, 18 (26.1%) were positive. After Leogane's fifth MDA, most symptomatic persons had undetectable levels of filarial antigen by ICT. Free symptomatic treatment may motivate some people to report symptoms and seek care.

Anthelmintics↗

Residual spatial correlation between geographically referenced observations: a Bayesian hierarchical modeling approach.

BACKGROUND: Analytic methods commonly used in epidemiology do not account for spatial correlation between observations. In regression analyses, this omission can bias parameter estimates and yield incorrect standard error estimates. We present a Bayesian hierarchical model (BHM) approach that accounts for spatial correlation, and illustrate its strengths and weaknesses by applying this modeling approach to data on Wuchereria bancrofti infection in Haiti. METHODS: A program to eliminate lymphatic filariasis in Haiti assessed prevalence of W. bancrofti infection in 57 schools across Leogane Commune. We analyzed the spatial pattern in the prevalence data using semi-variograms and correlograms. We then modeled the data using (1) standard logistic regression (GLM); (2) non-Bayesian logistic generalized linear mixed models (GLMMs) with school-specific nonspatial random effects; (3) BHMs with school-specific nonspatial random effects; and (4) BHMs with spatial random effects. RESULTS: An exponential semi-variogram with an effective range of 2.15 km best fit the data. GLMM and nonspatial BHM point estimates were comparable and also were generally similar with the marginal GLM point estimates. In contrast, compared with the nonspatial mixed model results, spatial BHM point estimates were markedly attenuated. DISCUSSION: The clear spatial pattern evident in the Haitian W. bancrofti prevalence data and the observation that point estimates and standard errors differed depending on the modeling approach indicate that it is important to account for residual spatial correlation in analyses of W. bancrofti infection data. Bayesian hierarchical models provide a flexible, readily implementable approach to modeling spatially correlated data. However, our results also illustrate that spatial smoothing must be applied with care.

Animals↗

Ultrasonographic examination of Haitian children with lymphatic filariasis: a longitudinal assessment in the context of antifilarial drug treatment.

To assess the clinical findings associated with detection of adult Wuchereria bancrofti worms on ultrasound, 186 schoolchildren in a filariasis-endemic area of Haiti underwent physical and ultrasonographic examinations. The filaria dance sign (FDS) of adult W. bancrofti was detected in the inguinal and crural lymphatics of 28 (15%) children. FDS detection was more common in older children (P = 0.003) and in those with a history of inguinal lymph node inflammation (P = 0.002) or crural lymphadenopathy on physical exam (P = 0.01). Twenty-five FDS-positive children were reexamined after three annual cycles of mass treatment for lymphatic filariasis (LF). The total number of adult worm nests detected by ultrasound decreased from 29 to 4 (P </=0.0001). FDS and lymphangiectasia were detected in the intrascrotal (N = 3) and inguinal (N = 1) lymphatic vessels of three postpubescent boys. This study demonstrates clinical and subclinical findings of LF in FDS-positive children.

Adolescent↗

Clinical correlates of filarial infection in Haitian children: an association with interdigital lesions.

To assess clinical findings associated with Wuchereria bancrofti infection, 192 school children in a filariasis-endemic area of Haiti underwent physical and ultrasonographic examinations and testing for circulating filarial antigen (CFA). The CFA-positive children were more likely than CFA-negative children to have severe interdigital lesions (> or = 1 macerated lesion with involvement of > or = 4 toe web spaces) (P < 0.0001) and inguinal (P = 0.003) or crural (P = 0.004) lymph node pathology. In multivariate analysis, CFA positivity remained a significant predictor for severe interdigital lesions (P = 0.006) and inguinal lymph node pathology (P = 0.05). Ultrasound detected adult worms and lymphangectasia (diameter = 2.0-4.0 mm) in 11 (10.8%) CFA-positive children. Among CFA-positive children, ultrasonographic detection of adult worms was associated with inguinal (P = 0.01) and crural (P = 0.004) lymph node pathology and advanced pubertal stage (sexual maturity rating = 3-5) (P = 0.02). This is the first study to associate interdigital lesions with filarial infection in children.

Adolescent↗

The Leogane, Haiti demonstration project: decreased microfilaremia and program costs after three years of mass drug administration.

To support the global program to eliminate lymphatic filariasis (LF), well-monitored demonstration projects are important for defining the relationship between coverage and reductions in microfilaremia. We are using mass treatment with diethylcarbamazine (DEC) and albendazole in an effort to eliminate LF from Leogane, Haiti. Wuchereria bancrofti microfilaremia prevalence at baseline ranged from 0.8% to 15.9% in four sentinel sites. After three rounds of DEC-albendazole mass drug administration (MDA), both microfilaremia prevalence and intensity decreased dramatically. Mild and moderate adverse reactions after treatment were common, especially after the first MDA, but decreased after subsequent MDAs. Drug coverage for the first year was estimated to be 72%, but concerns about adverse reactions appeared to decrease drug coverage in the second MDA. As a result of community education efforts that focused on providing a greater understanding of adverse reactions, coverage increased dramatically for the third round. Program efficiency increased substantially; the costs per person treated for three rounds of MDA were 2.23 US dollars, 1.96 US dollars, and 1.30 US dollars per person, respectively. The Leogane experience highlights the importance of adapting community education and mobilization campaigns to achieve and maintain good coverage.

Albendazole↗

Spatial clustering of filarial transmission before and after a Mass Drug Administration in a setting of low infection prevalence.

BACKGROUND: In the global program for the elimination of lymphatic filariasis (LF) longitudinal assessment of the prevalence of microfilaremia and antigenemia is recommended to monitor the effect of mass treatment on transmission. Additional monitoring tools such as entomologic and antibody methods may be useful in identifying residual foci of infection. In this study, we characterized serologic markers of infection and exposure spatially both before and after mass treatment, in an area of initial low Wuchereria bancrofti infection prevalence. METHODS: Consenting persons in the sentinel community were tested for circulating microfilaria and antigen (by immunochromatographic test) before and after the 1st annual mass drug administration of diethylcarbamazine and albendazole. A cohort of 161 persons provided serum specimens both years that were tested for antifilarial IgG (1 and 4) antibody. Every house was mapped using a differential Global Positioning System; this information was linked to the serologic data. W. bancrofti infection in the mosquito vector was assessed with year-round collection. Multiple linear regression was used to investigate the influence of antigen-positive persons on the antifilarial antibody responses of antigen-negative neighbors. RESULTS: After mass treatment, decreases were observed in the sentinel site in the overall prevalence of antigen (10.4% to 6.3%) and microfilaremia (0.9 to 0.4%). Of the persons in the cohort that provided serum specimens both years, 79% received treatment. Antigen prevalence decreased from 15.0% to 8.7%. Among 126 persons who received treatment, antigen and antifilarial IgG1 prevalence decreased significantly (p = 0.002 and 0.001, respectively). Among 34 persons who did not receive treatment, antifilarial IgG1 prevalence increased significantly (p = 0.003). Average antifilarial IgG1 levels decreased in households with high treatment coverage and increased in households that refused treatment. Each 10-meter increase in distance from the residence of a person who was antigen-positive in 2000 was associated a 4.68 unit decrease in antifilarial IgG1 level in 2001, controlling for other factors (p = 0.04). DISCUSSION: Antifilarial antibody assays can be used as a measure of filarial exposure. Our results suggest that micro-scale spatial heterogeneity exists in LF exposure and infection. Treatment appeared to be associated with reduced exposure at the sub-community level, suggesting the need to achieve high and homogeneous coverage. Public health messages should note the benefits of having one's neighbors receive treatment with antifilarial drugs.

Journal Article↗

Willingness to pay for prevention and treatment of lymphatic filariasis in Leogane, Haiti.

BACKGROUND: Lymphatic filariasis (LF) affects more than 120 million people worldwide. Efforts to eliminate this disease require sustained community participation. This study explores community valuation of LF elimination efforts by estimating household and community willingness to pay (WTP) for the prevention of transmission and treatment of filarial lymphedema in the community of Leogane, Haiti. METHODS: A contingent valuation survey was used to assess individual WTP for specific prevention and treatment interventions. A 2-dimensional Monte Carlo simulation was developed to estimate confidence limits in mean WTP and to generate a distribution of WTP for the community, accounting for uncertainty in regression coefficients and variability within the population. RESULTS: Mean WTP was estimated to be $5.57/month/household (95% CL: $4.76, $6.72) to prevent disease transmission, and $491/yr (95% CL: $377, $662) for treatment of lymphedema for one person. Based on the estimated distributions, 7% and 39% of households were not willing to pay for prevention and treatment, respectively. CONCLUSIONS: These results suggest that the majority of the community places a positive value on both prevention and treatment of LF. Mean WTP provides a useful monetary estimate of overall societal benefit of LF prevention and treatment programs. However, for interventions which require broad and sustained community participation, the lower end of the distribution of WTP has additional implications. Cost recovery policies may result in inadequate participation and longer program duration.

Journal Article↗

Histopathologic improvement with lymphedema management, Léogâne, Haiti.

In countries where bancroftian filariasis is endemic, lymphedema of the leg is a public health problem, particularly for women, who are disproportionately affected. We investigated the effect of basic lymphedema management (hygiene, skin care, and lower limb movement and elevation) on the histologic features of lymphedema. A total of 118 skin-punch biopsy specimens were collected from the legs of 91 patients enrolled in a lymphedema treatment clinic in Léogâne, Haiti. Follow-up biopsy specimens were collected from 27 patients succeeds, equals 12 months later. Keratinocyte hyperproliferation, condensed dermal collagen, and mononuclear perivascular infiltrate increased with lymphedema stage, which suggested progressive chronic inflammation and fibrosis. Follow-up biopsies showed reductions in perivascular mononuclear infiltrate in the superficial dermis (41% decrease in prevalence), perivascular fibrosis in the deep dermis (58% decrease), and periadnexal mononuclear infiltrate (53% decrease). These data suggest that the clinical improvement commonly observed with basic lymphedema management has a histologic basis.

Adolescent↗

Community- and individual-level determinants of Wuchereria bancrofti infection in Leogane Commune, Haiti.

We conducted a school-based assessment of the geographic distribution of Wuchereria bancrofti infection in Leogane Commune, Haiti, using the immunochromatographic test. In multivariate analyses performed using generalized linear mixed models, children attending schools in the foothills and plains were 3.95 (95% confidence interval [CI] = 1.28-12.23) and 23.56 (95% CI = 8.99-61.79) times as likely to be infected, respectively, as children attending mountain schools. Infection prevalence decreased with increasing altitude, but some local foci of infection were detected at higher altitudes. Higher school tuition, a marker of socioeconomic status (SES), was not associated with decreased infection prevalence. Our results indicate that although the force of infection in Leogane Commune is greatest below 70 meters above sea level, higher altitude communities are not exempt from infection. Lymphatic filariasis (LF) elimination programs should consider extending infection mapping activities to presumed non-LF altitudes. In addition, higher SES does not confer protection against W. bancrofti infection.

Animals↗

Community-wide reduction in prevalence and intensity of intestinal helminths as a collateral benefit of lymphatic filariasis elimination programs.

Annual mass treatment with antifilarial drugs is the cornerstone of the global program to eliminate lymphatic filariasis (LF). Although the primary goal of the program is to interrupt transmission of LF, additional public health benefits also are expected because of the known anthelminthic properties of these drugs. Since rapid re-infection with intestinal helminths occurs following treatment, annual de-worming may not be sufficient to produce a lasting reduction in the prevalence and intensity of these infections. We conducted stool examinations in four sentinel communities before and approximately nine months after each of two rounds of mass drug administration (MDA) with diethylcarbamazine and albendazole in the context of an LF elimination program in Leogane, Haiti. At baseline, overall Ascaris, Trichuris, and hookworm infection prevalences were 20.9%, 34.0%, and 11.2%, respectively (n = 2,716 stools). Nine months after the second MDA, Ascaris, Trichuris and hookworm prevalences had decreased significantly, to 14.1%, 14.6%, and 2.0%, respectively (n = 814 stools). Infection intensity decreased significantly for all three parasites as well. These results demonstrate that substantial reductions in intestinal helminth infections are associated with mass treatment of filariasis in Haiti and are consistent with the conclusion that high levels of coverage for the LF program can decrease transmission of geohelminths.

Adolescent↗

Geographic distribution of lymphatic filariasis in Haiti.

Although lymphatic filariasis is known to have been endemic in Haiti since at least the mid 1700s, a national filariasis survey has never been conducted. As a first step in the national program to eliminate filariasis, we collected blood in January-April 2001 from 50-250 school children (6-11 years old) in all 133 communes of the country using an adaptation of the lot quality assurance sampling method. Of 22,365 children tested, 901 (4.0%) were positive for circulating Wuchereria bancrofti antigen. When weighted by commune population, the overall national antigen prevalence in this age group was 7.3%. Infected children were found in 117 (87.9%) communes, the most heavily affected areas being concentrated in the northern part of the country. In only 16 (12.1%) communes were all 250 children antigen negative. Thus, W. bancrofti infection in Haiti is much more widespread than previously realized; virtually the entire population of the country may be considered at risk of infection.

Animals↗

A Framework for Decision-Making for Mass Distribution of Mectizan(R) in Areas Endemic for Loa loa.

BACKGROUND: The occurrence of Loa loa encephalopathy following mass treatment of onchocerciasis with Mectizan(R) has adversely affected onchocerciasis control efforts in central Africa. Persons with very high densities of L. loa microfilaremia are at increased risk of encephalopathy, but little is known about the geographic distribution of these persons within central Africa. RAPLOA, a new technique that correlates the proportion of community members reporting a history of eyeworm with the prevalence of high-intensity L. loa microfilaremia in that community, may be useful for rapid assessment of areas at potential risk of treatment-related L. loa encephalopathy. Validation of RAPLOA is ongoing. The operational and risk-reduction advantages of RAPLOA over the current technique of village-by-village rapid epidemiologic assessment for onchocerciasis (REA) are unknown. METHODS: We developed a decision model to compare four strategies for minimizing sequelae of L. loa encephalopathy following mass treatment with Mectizan(R) in areas co-endemic for onchocerciasis and loiasis: REA; RAPLOA with threshold eyeworm prevalences of 40% and 20% (RAPLOA-40 and RAPLOA-20, respectively); and combined REA/RAPLOA-40. RESULTS: In the model, all four strategies significantly reduced risk of death and neurologic complications from L. loa encephalopathy, but RAPLOA-20 and REA resulted in half as many such cases as did RAPLOA-40 or combined REA/RAPLOA-40. CONCLUSION: RAPLOA is likely to be useful programmatically in reducing risk of L. loa encephalopathy following mass treatment with Mectizan(R). It also may be cost-saving. Before full-scale implementation, additional data are needed on geographic clustering of high-density L. loa microfilaremia and on RAPLOA's reliability and cost.

Journal Article↗

Characterization of antibody responses to Wolbachia surface protein in humans with lymphatic filariasis.

Symbiotic Wolbachia organisms of filarial nematodes have received much attention as possible chemotherapy targets and disease-causing organisms. In order to further investigate the association between anti-Wolbachia immune responses and chronic filarial disease in humans, antibody responses to Wolbachia surface protein (WSP) were assayed in serum samples collected from 232 individuals living in Leogane, Haiti, an area where Wuchereria bancrofti infection is endemic, and from 67 North Americans with no history of lymphatic filariasis. As opposed to antifilarial antibody responses, which were largely influenced by the patient's infection status, the prevalence and levels of anti-WSP immunoglobulin G (IgG) antibodies among individuals with lymphedema or hydrocele were significantly greater than those in gender- and infection-matched individuals without disease. In at least one case, the anti-WSP IgG response was coincident with the onset of lymphedema development, and among anti-WSP-positive women with lymphedema, anti-WSP IgG levels were negatively correlated with the duration of lymphedema. The presence of anti-WSP IgG was also associated with the severity of inguinal adenopathy among men with hydrocele. In addition to the presence of anti-WSP antibodies among Haitians, 15 of 67 (22%) serum samples collected from individuals from North America, where filariasis is not endemic, were also positive for anti-WSP antibodies. In comparison to those from Haitians, anti-WSP antibodies from North Americans primarily recognized a distinct region of WSP located within the highly conserved second transmembrane domain. The results of this study demonstrate that anti-WSP antibody responses are associated with the presence of chronic filarial morbidity and not filarial infection status in humans and suggest that WSP should be further studied as a potential trigger for the development of filarial disease.

Adolescent↗

Highly endemic, waterborne toxoplasmosis in north Rio de Janeiro state, Brazil.

In Campos dos Goytacazes, northern Rio de Janeiro state, Brazil, reports of uveitis consistent with toxoplasmosis led to a survey of the prevalence and risk factors for Toxoplasma gondii infection in 1997-1999. The survey population was selected randomly from schools, randomly chosen communities, and an army battalion. Serum samples from 1,436 persons were tested. With results adjusted for age, 84% of the population in the lower socioeconomic group was seropositive, compared with 62% and 23% of the middle and upper socioeconomic groups, respectively (p<0.001). When multivariate analysis was performed, drinking unfiltered water was found to increase the risk of seropositivity for the lower socioeconomic (odds ratio [OR]: 3.0, 95% confidence interval [CI] 1.3 to 6.9) and middle socioeconomic (OR: 1.7, 95% CI 1.2 to 2.3) populations. We also found a high T. gondii seroprevalence in this Brazilian community. Drinking unfiltered water increased the risk of T. gondii seropositivity, indicating the potential importance of oocyst transmission in water in this region.

Adolescent↗